Conductivity of polymer films formed by PEO-containing intramolecular polycomplexes

Abstract

Block copolymers comprising chemically complementary poly(ethylene oxide)/polyacrylamide have been evaluated as proton conducting materials. With this aim in mind, two series of block copolymers PAAm-b-PEO (DBC) and PAAm-b-PEO-b-PAAm (TBC) with the variable PEO-block length have been synthesized. Polymer electrolyte membranes (PEM) based on DBCs, TBCs and also their partially hydrolyzed derivatives (DBChydr and TBChydr respectively) were prepared by using a solution casting technique, and their ion (proton) conductivity was studied at the ambient temperature and at different relative humidity (RH). The rise in RH from 33% to 98% resulted in the increase in conductivity of DBC and TBC membranes up to 10−4 S∙cm−1. The study of the kinetics of the water absorption at 98% RH showed that the introduction of –COOH-groups into PAAm chains could accelerate the process of water absorption. The increase in conductivity of DBC and TBC membranes with the PEO-block lengthening has been noticed. This proved the significant contribution of oxyethylene chains in ensuring the conductivity. The reason for the application of DBCs and TBCs as potantial ion-conducting membranes have been discussed.